Anyone who travels on holiday to a country where IS might operate is an idiot. Full stop. We cannot, as you say, save them in this scenario.
Personally, I think the same applies to aid workers in terms of inability of saving them. The two I know who visit regularly go with no expectation of being saved, and would be mortified if anyone tried to do so. On that condition, I admire their conviction and see no need for a travel ban.
I think the Government advice on travel to such places needs beefing up.